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| 2. |
- Kaptoge, S., et al.
(författare)
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World Health Organization cardiovascular disease risk charts: revised models to estimate risk in 21 global regions
- 2019
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Ingår i: Lancet Global Health. - : Elsevier BV. - 2214-109X. ; 7:10
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Tidskriftsartikel (refereegranskat)abstract
- Background To help adapt cardiovascular disease risk prediction approaches to low-income and middle-income countries, WHO has convened an effort to develop, evaluate, and illustrate revised risk models. Here, we report the derivation, validation, and illustration of the revised WHO cardiovascular disease risk prediction charts that have been adapted to the circumstances of 21 global regions. Methods In this model revision initiative, we derived 10-year risk prediction models for fatal and non-fatal cardiovascular disease (ie, myocardial infarction and stroke) using individual participant data from the Emerging Risk Factors Collaboration. Models included information on age, smoking status, systolic blood pressure, history of diabetes, and total cholesterol. For derivation, we included participants aged 40-80 years without a known baseline history of cardiovascular disease, who were followed up until the first myocardial infarction, fatal coronary heart disease, or stroke event. We recalibrated models using age-specific and sex-specific incidences and risk factor values available from 21 global regions. For external validation, we analysed individual participant data from studies distinct from those used in model derivation. We illustrated models by analysing data on a further 123 743 individuals from surveys in 79 countries collected with the WHO STEPwise Approach to Surveillance. Findings Our risk model derivation involved 376 177 individuals from 85 cohorts, and 19 333 incident cardiovascular events recorded during 10 years of follow-up. The derived risk prediction models discriminated well in external validation cohorts (19 cohorts, 1 096 061 individuals, 25 950 cardiovascular disease events), with Harrell's C indices ranging from 0.685 (95% CI 0 . 629-0 741) to 0.833 (0 . 783-0- 882). For a given risk factor profile, we found substantial variation across global regions in the estimated 10-year predicted risk. For example, estimated cardiovascular disease risk for a 60-year-old male smoker without diabetes and with systolic blood pressure of 140 mm Hg and total cholesterol of 5 mmol/L ranged from 11% in Andean Latin America to 30% in central Asia. When applied to data from 79 countries (mostly low-income and middle-income countries), the proportion of individuals aged 40-64 years estimated to be at greater than 20% risk ranged from less than 1% in Uganda to more than 16% in Egypt. Interpretation We have derived, calibrated, and validated new WHO risk prediction models to estimate cardiovascular disease risk in 21 Global Burden of Disease regions. The widespread use of these models could enhance the accuracy, practicability, and sustainability of efforts to reduce the burden of cardiovascular disease worldwide. Copyright (C) 2019 The Author(s). Published by Elsevier Ltd.
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- Morgan, L. A., et al.
(författare)
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The dynamic floor of Yellowstone Lake, Wyoming, USA : The last 14 k.y. of hydrothermal explosions, venting, doming, and faulting
- 2023
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Ingår i: Bulletin of the Geological Society of America. - 0016-7606. ; 135:3-4, s. 547-574
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermal explosions are significant potential hazards in Yellowstone National Park, Wyoming, USA. The northern Yellowstone Lake area hosts the three largest hydrothermal explosion craters known on Earth empowered by the highest heat flow values in Yellowstone and active seismicity and deformation. Geological and geochemical studies of eighteen sublacustrine cores provide the first detailed synthesis of the age, sedimentary facies, and origin of multiple hydrothermal explosion deposits. New tephrochronology and radiocarbon results provide a four-dimensional view of recent geologic activity since recession at ca. 15–14.5 ka of the >1-km-thick Pinedale ice sheet. The sedimentary record in Yellowstone Lake contains multiple hydrothermal explosion deposits ranging in age from ca. 13 ka to ~1860 CE. Hydrothermal explosions require a sudden drop in pressure resulting in rapid expansion of high-temperature fluids causing fragmentation, ejection, and crater formation; explosions may be initiated by seismicity, faulting, deformation, or rapid lake-level changes. Fallout and transport of ejecta produces distinct facies of subaqueous hydrothermal explosion deposits. Yellowstone hydrothermal systems are characterized by alkaline-Cl and/or vapor-dominated fluids that, respectively, produce alteration dominated by silica-smectite-chlorite or by kaolinite. Alkaline-Cl liquids flash to steam during hydrothermal explosions, producing much more energetic events than simple vapor expansion in vapor-dominated systems. Two enormous explosion events in Yellowstone Lake were triggered quite differently: Elliott’s Crater explosion resulted from a major seismic event (8 ka) that ruptured an impervious hydrothermal dome, whereas the Mary Bay explosion (13 ka) was triggered by a sudden drop in lake level stimulated by a seismic event, tsunami, and outlet channel erosion.
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| 7. |
- Power, M. J., et al.
(författare)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Tidskriftsartikel (refereegranskat)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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| 8. |
- Addie, Graeme, et al.
(författare)
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Pipeline design characteristics of some industrial paste-like slurries
- 2005
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Ingår i: Conference Proceedings - First Extractive Metallurgy Operators' Conference. - : The Australian Institute of Mining and Metallurgy. ; , s. 147-154
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Konferensbidrag (refereegranskat)abstract
- There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.
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- Goni, Maria Fernanda Sanchez, et al.
(författare)
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The ACER pollen and charcoal database : a global resource to document vegetation and fire response to abrupt climate changes during the last glacial period
- 2017
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 9:2, s. 679-695
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Tidskriftsartikel (refereegranskat)abstract
- Quaternary records provide an opportunity to examine the nature of the vegetation and fire responses to rapid past climate changes comparable in velocity and magnitude to those expected in the 21st-century. The best documented examples of rapid climate change in the past are the warming events associated with the Dansgaard-Oeschger (D-O) cycles during the last glacial period, which were sufficiently large to have had a potential feedback through changes in albedo and greenhouse gas emissions on climate. Previous reconstructions of vegetation and fire changes during the D-O cycles used independently constructed age models, making it difficult to compare the changes between different sites and regions. Here, we present the ACER (Abrupt Climate Changes and Environmental Responses) global database, which includes 93 pollen records from the last glacial period (73-15 ka) with a temporal resolution better than 1000 years, 32 of which also provide charcoal records. A harmonized and consistent chronology based on radiometric dating (C-14, U-234/Th-230, optically stimulated luminescence (OSL), Ar-40/Ar-39-dated tephra layers) has been constructed for 86 of these records, although in some cases additional information was derived using common control points based on event stratigraphy. The ACER database compiles metadata including geospatial and dating information, pollen and charcoal counts, and pollen percentages of the characteristic biomes and is archived in Microsoft Access (TM) at https://doi. org/10.1594/PANGAEA. 870867.
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- Mendoza, Pablo A, et al.
(författare)
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Oral anticoagulation for patients with atrial fibrillation in the ED : RE-LY AF registry analysis.
- 2022
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Ingår i: Journal of Thrombosis and Thrombolysis. - : Springer Nature. - 0929-5305 .- 1573-742X. ; 53:1, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- Oral anticoagulation (OAC) reduces stroke risk in patients with atrial fibrillation (AF). We sought to determine predictors of OAC initiation in AF patients presenting to the emergency department (ED). Secondary analysis of the RE-LY AF registry which enrolled individuals from 47 countries between 2007 and 2011 who presented to an ED with AF and followed them for 1 year. A total of 4149 patients with AF as their primary diagnosis who were not already taking OAC and had a CHA2DS2-VASc ≥ 1 for men or ≥ 2 for women were included in this analysis. Of these individuals, 26.8% were started on OAC (99.2% vitamin K antagonists) in the ED and 29.8% were using OAC one year later. Factors associated with initiating OAC in the ED included: specialist consultation (relative risk [RR] 1.84, 95%CI 1.44-2.36), rheumatic heart disease (RR 1.60, 95%CI 1.29-1.99), persistence of AF at ED discharge (RR 1.33, 95%CI 1.18-1.50), diabetes mellitus (RR 1.32, 95%CI 1.19-1.47), and hospital admission (RR 1.30, 95%CI 1.14-1.47). Heart failure (RR 0.83, 95%CI 0.74-0.94), antiplatelet agents (RR 0.77, 95%CI 0.69-0.84), and dementia (RR 0.61, 95%CI 0.40-0.94) were inversely associated with OAC initiation. Patients taking OAC when they left the ED were more likely using OAC at 1-year (RR 2.81, 95%CI 2.55-3.09) and had lower rates of death (RR 0.55, 95%CI 0.38-0.79) and stroke (RR 0.59, 95%CI 0.37-0.96). In patients with AF presenting to the ED, prompt initiation of OAC and specialist involvement are associated with a greater use of OAC 1 year later and may result in improved clinical outcomes.
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| 14. |
- Sellgren, Anders, et al.
(författare)
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Technical-economical feasibility of using centrifugal pumps in high-density thickened tailings slurry systems
- 2005
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Ingår i: Paste 2005. - Perth, WA : Australian Centre for Geomechanics. ; , s. 195-204
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Konferensbidrag (refereegranskat)abstract
- Pumping simulated tailings slurry at a high solids content has been investigated at the GIW Hydraulic Testing Laboratory in a 0.075 m diameter loop with a centrifugal pump with an auger-like inducer. The results and earlier experiences from the Laboratory and some reported data indicate that viscous slurries characterized by shear stresses in pipeline transportation of 100 to 200 Pa can be pumped effectively with centrifugal pumps. Stresses in this range were reported in pipeline, flume and viscometer experiments with typical base metal tailings slurries at concentrations by volume of 44% in pilot-scale thickening tests. The corresponding concentration by mass,70%, gave a non-segregating mixture which could be disposed at slopes of about 4%. With this type of slurry, an overall economical comparison here indicates that centrifugal pumps are a cost-effective alternative also in high pressure applications (4 MPa) corresponding to a distance of 1000 m when pumping 300 tonnes per hour.
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| 15. |
- Sellgren, Anders, et al.
(författare)
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The feasibility of transporting contaminated sediments as a slurry using centrifugal pumps
- 2005
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Ingår i: Remediation of contaminated sediments--2005. - Columbus, Ohio : Battelle Press.
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Konferensbidrag (refereegranskat)abstract
- Pumping a simulated sediment slurry at a low water content has been investigated at the GIW Hydraulic Testing Laboratory in a 3 inch (0.075 m) diameter loop with a centrifugal pump with an auger-like inducer. The results and earlier reported data from the Laboratory indicate that viscous sediments characterized by yield stresses in the range of about 2 to 4 psf (100 to 200 Pa) can be pumped effectively with centrifugal pumps. With yield stresses of up to 4 psf (200 Pa), the pressure requirement to overcome pipe friction for pipeline diameters of 4 and 16 inch (0.1 and 0.4 m), may be 0.35 and 0.09 psi per ft ( 8 and 2 kPa per m) of pipeline, respectively. Several pumps in series are therefore required also for moderate transportation distances. The results indicate that centrifugal pumps can be a cost-effective alternative for handling and transportation of sediments at a low water content.
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| 16. |
- Spanbauer, Trisha L., et al.
(författare)
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Yellowstone Lake Coring Projects : Research with a History
- 2018
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Ingår i: Limnology and Oceanography Bulletin. - : Wiley. - 1539-607X .- 1539-6088. ; 27:1, s. 6-10
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Tidskriftsartikel (refereegranskat)abstract
- The Yellowstone National Park ecosystem is a product of dynamic earth system processes, which have been of interest to scientists and the public since the park's discovery. Here, we outline the history of two successive generations of scientific collaboration in Yellowstone National Park. Early collaboration was spurred by the discovery of an unknown diatom species found in Yellowstone Lake. This prompted the first coring project in 1992 that described the morphological evolution of that species and the paleoenvironmental conditions during which it evolved. About twenty years later, the group was brought together again, with the addition of early career scientists, for a coring project focused on hydrothermal activity in the Yellowstone Lake basin. We discuss the ongoing research and analyses of core material, and conclude with the benefits of working in multigenerational interdisciplinary research groups.
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| 17. |
- Whitlock, L., et al.
(författare)
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Effect of near-wall lift on frictional characteristics of sand slurries
- 2004
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Ingår i: Papers presented at Hydrotransport, 16th international conference. - Cranfield, UK : BHR Group Limited. - 1855980541 ; , s. 443-454
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Konferensbidrag (refereegranskat)abstract
- The frictional characteristics of a fine-sand and medium-sand slurry were evaluated experimentally in a 0.1 m diameter pipeline loop system at the GIW Hydraulic Test Laboratory. The median particle sizes were 85 and 400 μm. For velocities of practical interest in the interval 1.5 to 3 m/s, and volumetric concentrations of solids from 12 to 34%, the fine-sand slurry behaved essentially as an equivalent fluid. With the medium sand at 17% concentration, the excess losses over those of water were high at low velocities, decreased with increasing velocity and dropped below the equivalent-fluid curve at about 4.2 m/s. This behaviour was related to an inertial hydrodynamic lift force that is effective in driving particles in the medium-sand size range away from the wall. A lift coefficient is defined for the inertial lift force associated with the log-law turbulent velocity profile. In the buffer zone nearer the pipe wall, it is proposed that this lift diminishes in a way that depends on a dimensionless ratio that includes the particle radius and the shear velocity. This trend is seen to be in general agreement with both the medium-sand and the fine-sand data.
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